Question

By the reaction of carbon and oxygen, a mixture of $CO$ and $C{O}_2$ is obtained. The mass ratio of the mixture obtained when $20$ g of $O_2$ reacts completely with $12$ g of carbon is:

• A. $m_{CO}:m_{C{O}_2}=21:11$
• B. $m_{CO}:m_{C{O}_2}=11:21$
• C. $m_{CO}:m_{C{O}_2}=22:14$
• D. $m_{CO}:m_{C{O}_2}=14:22$

Answer 1

Answer: (A)

$m_{CO}:m_{C{O}_2}=21:11$

Given:
Moles of $C$ $=\frac{12}{12}=1$

Moles of $O_2=\frac{20}{32}=0.625$
Reaction:

Let the moles of oxygen which react with C to form $C{O}_2$ be $x$
$2C+O_2\to 2CO$
$1-x$ $(1-x)/2$ $1-x$
$C+O_2\to C{O}_2$
$x$ $x$ $x$
We have, $(1-x)/2+x=0.625$

Hence, $x=0.25$

So, moles of carbon dioxide is equal to 0.25 and moles of carbon monoxide is equal to 0.75 .

So, mass of CO produced is 21 g and mass of $C{O}_2$ produced is 11 g.